The brain is increasingly being recognized as a sanctuary site for metastatic tumor cells in women with HER2-overexpressing breast cancer who receive trastuzumab (Herceptin) therapy. There are no approved or widely accepted treatments for brain metastases other than steroids, cranial radiotherapy, and surgical resection. However, some of these therapies may have serious consequences on the quality of life of the patient, particularly with respect to cognitive function. Identifying the molecular alterations in these lesions may help researchers develop new therapies that may improve survival. We will study the primary tumors and metastasis in different sites and evaluate different markers such as Her2, epidermal growth factor receptor (EGFR), estrogen receptor (ER), prostate receptor (PR), and p53 using immunohistochemistry and chromogenic in situ hybridization (CISH) and then correlate this data with other clinico-pathologic parameters. Later on, we will evaluate the differentiated miRNA expression profiles in both the primary cancers and the metastases.